This invention is concerned with improvements in or relating to folding machines, more especially edge folding machines for progressively folding over a marginal portion of a workpiece, e.g. a shoe upper.
The phrase "an edge folding machine of the type herein defined" where used herein is to be understood as referring to "an edge folding machine for progressively folding over a marginal portion of a workpiece, comprising folding instrumentalities arranged at an operating locality of the machine, workpiece feeding means for feeding a workpiece step-by-step through the operating locality, control means whereby the feed length of each feed movement of the workpiece feeding means can be varied during the operation of said workpiece feeding means, a reciprocatory slitting mechanism, operable in timed relation with the operation of the workpiece feeding means, for slitting the marginal portion of a workpiece as it is fed to the operating locality of the machine by the workpiece feeding means, and actuating means for causing the slitting mechanism to operate".
In using such a machine, conventionally when operating on an "outside" (i.e. convex) curve along the periphery of a workpiece, the feed length referred to above is shortened, thus to facilitate pleating of the material of the folded-over portion. It will of course be appreciated that, where such a curve arises, there is excess material in the folded-over portion in comparison with the surface of the workpiece to which the folded-over portion is to be secured. Conversely when operating on an "inside" (i.e. concave) curve, where the amount of material in the folded-over portion is less than the material of the surface to which it is to be secured, the slitting mechanism is caused to provide a series of slits in the portion to be folded over, prior to such folding, thus to facilitate its subsequent securing without distortion. Slitting is usually effected with the feed length selected at a maximum in order to avoid the provision of a larger number of closely spaced slits (the slitting arrangement making one slit for each feed movement of the workpiece feeding means).
In order to accommodate the different feed length requirements, the control means of edge folding machines of the type herein defined conventionally comprises adjustable means whereby a maximum setting and a minimum setting can be made for the feed length.
Furthermore, it has usually been the case that the adjustable setting means is biased towards the maximum feed setting, although it has been proposed to bias the adjustable means towards the minimum feed setting. Thus, for example, in one machine of the type herein defined, operator-controlled means in the form of a treadle has been provided to facilitate altering the setting of the feed length under the control of the operator according to the edge contour of the workpiece being operated upon, and also to cause the slitting arrangement to operate as required by said contour, the treadle being so arranged that the maximum feed length is selected whenever the slitting arrangement is caused thus to operate.
Again, by way of further example, in another machine of the type herein defined, the feed length is automatically controlled according to the edge contour of the workpiece being operated upon, said contour being sensed e.g. by photo-electric sensing means. In this machine the minimum feed length setting is selected only when an outside curve is sensed, the maximum setting being otherwise used (including any operation involving the operation of the slitting arrangement).
It will thus be appreciated that if the maximum feed setting is to be used during the slitting arrangement, such maximum setting has to be determined according to what feed setting can be tolerated by the curvature of the "inside" curves. A substantial part of the periphery of a workpiece may, however, be relatively straight and thus capable of being folded over using a higher feed length setting than the maximum in fact set because of the "inside" curves, so that in a working day operating time may be lost.
It is one of the various objects of the present invention to overcome this disadvantage in existing machines of the type herein defined. To this end, the invention provides, as one of its several features, an edge folding machine of the type above defined wherein the control means comprises first adjusting or setting means whereby a maximum setting and a minimum setting can be made for the feed length of each feed movement of the workpiece feeding means, and second setting means whereby a further setting can be made for said feed length, the machine also comprising further actuating means which operates when the first-mentioned actuating means is operated, and thus when being effective to ensure that the operation of said further actuating means being effective to ensure that the setting of the feed length, while the slitting arrangement is operating, is not less than said further setting therefor made by means of the second setting means.
It will thus be appreciated that by providing a further setting independently of the maximum setting of the feed length, an optimum maximum feed length can be achieved for straight line operating. Furthermore, by providing an adjustment facility by which the further setting can be made for slitting purposes, an optimum "slitting" feed length can also be achieved.
The further setting which is thus made provides merely a "minimum slitting" feed length setting. If the feed length setting in use during an operation is greater than such "minimum slitting" setting, then operation of the further actuating means will be of no effect.
A machine in accordance with the invention may be arranged so that the feed length setting is biased towards a maximum, but preferably a bias is provided, e.g. by spring means, towards a minimum setting as herein disclosed. In this way to achieve a "minimum slitting" feed length setting when the slitting arrangement is caused to operate, where the setting would otherwise be less than said "minimum slitting" setting, the further actuating means is arranged to act against the influence of such biasing means.
The further actuating means, which preferably comprises a solenoid, is conveniently arranged to act, directly or indirectly, on a lever forming part of the control means, the arrangement being such that the further actuating means is not secured to said lever but rather relies on abutting engagement so that, when the slitting arrangement is inoperative, the position of the lever, and thus the feed length setting, can be determined without the further actuating means being affected.
Furthermore, the "minimum slitting" setting can be varied, as appropriate to the workpiece to be operated upon, by varying the positional relationship between the further actuating means and the surface which is abuttingly engaged. This variation may be achieved in accordance with the invention by moving the further actuating means relative to such surface, but preferably the surface is provided by a linkage arrangement comprising a link capable of lengthwise, e.g. telescoping, adjustment, the link being pivotally connected to the lever of the control means. Where such a link is provided, adjustment is conveniently facilitated by the link comprising two portions, one threadedly received within the other, so that relative rotation is effective to shorten or lengthen the overall length of the link.
The first setting means of the machine preferably comprises a further lever fixedly connected to the first-mentioned lever, the two levers being mounted for pivotal movement on a shaft of the control means, rotation of which shaft is effective to vary the feed length setting of the workpiece feeding means. For providing maximum and minimum settings, the first setting means conveniently comprises adjustable stop means for the further lever, either in the form of conventional adjustable stop screws, or a series of apertures into which selectively stop pins may be inserted so as to extend into the path of movement of the further lever, or a combination of a series of apertures into which one pin may be so inserted, e.g. for the maximum setting, with an adjustable stop screw, e.g. for the minimum setting.
In using such a machine, the operator conveniently makes the maximum and minimum feed length settings, according to the edge contour of the workpiece to be operated upon, using the first setting means, and also makes the further setting, using the second setting means, according to the amount of slitting deemed appropriate for the "inside" curves of such workpiece.
It will be appreciated that the invention as set out above is applicable to both operator-controlled machines and also automatically controlled machines.